Gage with fixed spaced gaging elements and an axially movable gaging element therebetween



Sept. 6, 1966 P. w. JOHNSON 3,270,424

GAGE WITH FIXED SPACED GAGING ELEMENTS AND AN AXIALLY MOVABLE GAGINGELEMENT THEREBETWEEN Original Filed Aug. 5, 1959 2 Sheets-Sheet 1 I 2' mas YNVENTOR. PFIuL W JOHNSON Y mmmmw H TTOFPNE Y 3,2 70,424 IALLY Sept.6, 1966 P. w. JOHNSON 2 Sheets-Sheet 2 GAGE WITH FIXED SPACED GAGINGELEMENTS AND AN AX MOVABLE GAGING ELEMENT THEREBETWEEN 5. 1959 /43 m5 m7m3 Original Filed Aug.

INVENTOR. PHUL 1M JOHNSON United States Patent 3,270,424 GAGE WITH FIXEDSPACED GAGING ELEMENTS AND AN AXIALLY MOVABLE GAGING ELE- MENTTHEREBETWEEN Paul Johnson, Bloomfield, Conn., assiguor, by mesneassignments, to The Johnson Gage Company, Bloomfield, Conn., acorporation of Connecticut Original application Aug. 5, 1959, Ser. No.831,757. Divided and this application July 29, 1963, Ser. No. 299,684

10 Claims. (Cl. 33-174) This application is a division of applicationS.N. 831,757 filed August 5, 1959' and now abandoned.

The invention relates to a gage for measuring a screw threaded part andmay test as well for other components related to the thread such as thecentricity of a conical and/or cylindrical surface or bore with respectthereto and the squareness of one or more faces with respect to thethread. The invention also relates to a gage for measuring the accuracyof a groove, such as the groove on a turbine rotor which groove receivesa blade or a screw thread groove as well as a combination of the threadwith other structure related thereto to determine the relativeacceptability as to centricity, squareness and other factors which maybe desirable to be tested on a test part. thread.

It is an object of the invention to construct a thread gage of simpleconstruction which determines the acceptability of a screw thread andalso uses the thread gaging means as holding means for the test part fordetermining other characteristics of the test part such as squareness ofone or more surfaces and/or centricity of one or more surfaces includinga taper, a cylindrical bore and a cylindrical surface with respect tothe thread.

Another object is to construct a gage for rotatably mounting gagingmeans for a test part and having a pivotal frame for carrying one ormore indicators which frame is pivoted into and retained in gagingposition to determine other characteristics or components of the testpart when rotated with the gaging means.

Another object is to construct a gage for testing the accuracy of agroove by axial movement of one gage part with respect to another.

A still further object is to construct a simple gage to test a screwthread and to test the thread for lead error.

Other objects of the invention will be more apparent from the followingdescription when taken in connection with the accompanying drawingsillustrating preferred embodiments thereof in which:

FIG. 1 is a plan view of a gage for testing a screw thread for size andtesting other surfaces with respect to the screw thread;

FIG. 2 is an end view of the gage of FIG. 1;

FIG. 3 is a plan view of the gage of FIG. 1 with certain indicatorsmounting means retracted.

FIG. 4 is a enlarged longitudinal section through the thread gagingportion of the gage of FIGS. 1 to 3;

FIG. 5 is an end view of the gage of FIG. 4;

FIG. 6 is a section of a part of the gage of FIG. 4;

FIG. 7 is a side view partially in section of a gage for the bladegroove of a turbine;

FIG. 8 is a partial end view showing the gaging members of FIG. 7;

FIG. 9 is a view showing gaging members or means having contact points;

FIG. 10 is a view showing gaging members for gaging between the bottomand the outer flank of a turbine blade groove;

FIG. 11 is a view showing gaging members for a tur- This thread gagealso tests for lead of the.

for larger diameters as well.

3,270,424 Patented Sept. 6, 1966 ice bine blade groove having aplurality of serrations or grooves.

FIGS. 1 to 6 show a gage designed primarily for testing small diametersof test parts, although it is suitable This gage has a thread gagingmeans in which a pair of gaging elements is fixed and another gagingelement is axially movable as will be described hereinafter. In thisconstruction, a base or base member 93 rotatively receives a frame orframe member. The base 93 carries a pivoted frame 94 mounted on a pivot95 carried by the base. At least one indicator mounting means is carriedby the pivoted frame which includes a mounting pin. Four mounting pinsare shown namely 96, 97, 98 and 99 and indicator brackets 100a, 100b,1000, 100d, and 100e. Three of the mounting pins 96, 98, and 99 areshown as carrying an indicator bracket for receiving or supporting anindicator. The mounting pin 97 carries a transfer lever 101 which ispivotally mounted on the pin one end of which is adapted to engage asurface of a groove in the test part to test the centricity of thesurface with respect to the groove or thread. An indicator is carried bythe bracket 100a on the pin 96 and engages the other end of the transferlever 101. An indicator carried by the bracket 100bcarried by themounting pin 99 may be positioned to engage the periphery of the testpart to test the accuracy of the diameter thereof and the centricitythereof with respect to the thread. A second indicator mounted on abracket 1000 on the mounting pin 98 may engage the end surface of thetest part to test its dimension and squareness with respect to thethread. Many variations may be made in the use of this pivoted frame.

Means are provided to hold the pivoted frame 94 in gaging positionadjacent to the thread gaging means, the means particularly shownincludes a holding lever 103 pivotally mounted on a pin 104 andpropelled by a spring 105. The mounting lever when in gaging position,engages a locating stop 106 carried by the base and the holding leverthen engages the back end of the pivoted frame or particularly anangular surface 107 thereon so that the pivoted frame is held againstthe stop by the spring. By pressing the pivoted frame to the left, theholding lever is released and the indicators are swung away from thetest part so that it may be removed from the thread gaging means whichalso serve as holding means for the test part when rotating the frameand the test part. The base may carry other indicator mounting pins 108and 109. The pin 108 mounts a transfer lever 102 for engaging an endsurface of the test part and a second transfer lever 116 for engaging ataper surface on the test part. The pin 109 mounts an indicator bracket100d for an indicator for engaging the second transfer lever. Anotherbracket 100e is carried by the base to engage the transfer lever 102.

FIG. 4 shows the construction of a thread gaging means which may bemounted on the base 93. It includes a frame or frame member 111 having abearing for rotatable mounting the same on the base, the particularmeans shown being balls 112 receiving in ball grooves carried by theframe and the base. The frame carries a guide or guideway 113 formounting the operating means for axial movement on the frame. The guidein this construction constitutes central bore. Fixed thread gaging meansor elements 114 are secured to the frame in spaced relation such as byscrews 115. The thread gaging means 114 are of a diameter to receive thesmallest diameter of test thread so that if the test part does notthread thereon it is known to be too small. To test for oversize of aninternal thread of a test part, the guide 113 carries an axially movableoperating memthread.

ber 119 forming a part of the operating means. The operating membercarries an axially movable gaging means 120 which is received andslidable axially in the space or gap between the fixed thread gagingmeans 114. This gaging means 120 carries on its periphery cooperatingthread gaging means shown particularly as a single thread gaging ridge121 on opposite sides.

The operating means includes means to shift the operating member 119axially and hence to axially shift the cooperating gaging ridges 121.The means particularly shown includes a cam means 122 shown as flats onan operating lever 123 which is pivotally mounted in holes 124 carriedby the frame. Upon pressing the lever 123 the cam means 122 propels theoperating member 119 to the left to bring the cooperating gaging ridges121 into alignment with one of the thread spirals of the gaging members114 so that the test part may be threaded thereon. The operating meansalso include spring means for propelling the operating member and thethread ridges 121, for gaging engagement, in the opposite direction orto the right which means is shown as taper means or pins 125 on oppositesides of the frame slidably mounted in a laterally extending hearing orhole 126 and engaging a taper surface 127 in the operating member 119.Each taper pin 125 is pressed radially inwardly by a spring 128, thecompression of which may be adjusted by a screw 129 which backs up thespring.

Indicator means is carried by one of the members including the frame 111and the operating member 119 and engages the other member to indicatethe position of one member with respect to the other and therebyindicate whether or not the test part is within the allowabletolerances. In the construction particularly shown an indicator 132 issecured to the frame 111 such as by ascrew 133 which deforms a bushing134 to grip the stem of the indicator. The end of the frame, thecontactor C of the indicator engages the operating member 119 at thebottom of a hole 135 so that the relative position of the operatingmember and its cooperating gaging ridge 121 with respect to the frameand the gaging means 114 is indicated.

In operation the thread gaging ridge 121 is brought 'into alignment withthe adjacent one of the thread ridges on the fixed gaging members 114 bydepression of-the lever 123 and upon its release the springs 128 pressthe operating member to the right and brings the cooperating thread gageridges 121 into contact with the right hand flank of the test thread. Ifthe indicator 132 shows that the thread groove is to wide, the indicatorpointer will give a reading outside of the desired tolerance limits. Ifthe test thread is within the limits the indicator pointer will comewithin the tolerance limits allowed for the test The gage will alsoindicate any error in lead by watching the indicator as the test part isthreaded on the fixed gaging means 114. By noting the reading when thefirst thread of the test part is engaged by the gaging ridge 121 andupon continued rotation of the test thread onto the fixed thread gagingmembers 114 and noting changes in the indicator reading, which indicateschanges in relative position of the ridge 121 for succeeding threads. Ifthe reading on the indicator varies, this shows that the lead of thethread is faulty. An increasing reading on the indicator will show along lead and a decreasing reading will show a short lead.

The gage of FIG. 4 when mounted on the base of FIG. 3, provides a threadgage as well as a holding means for a test part. The base constitutes anindicator carrying member havingindicator mounting means and may haveone or more transfer levers to extend between a surface of the test partand an indicator. When the thread 'has been gaged, the test part isadvanced until an indicator such as an indicator reading from thetransfer lever 102 shows zero. Then by rotating the thread gaging meansand the test part held thereby, the centricity or squareness of othersurfaces of the test part with respect to the thread, as well as thedimension of the part having the surface, is determined. If theindicator readings do not change then the particular surface is squareor concentric with the thread.

The gage as shown in FIGS. 4 through 6 may be disconnected from the base93 by removal of the balls 112 from the ball race or groove and serve asa hand gage for testing the thread of a test part or it may be conveyedto a threaded hole in a large casting and an on the job check of anysuch thread may be made. With the gage mounted on the base of FIGS. 1 to3 the thread gaging means also constitutes means for holding the testpart. Rotation of the gage and of the gage and of the test part held bythe thread gaging means while mounted on the base, various tests may bemade as to squareness and centricity of various surfaces with respect tothe thread. The thread gaging means grips the test part sufiiciently sothat it remains set thereon and does not shift so that the test partwhen rotated will operate these various other indicators carried by thebase to test other surfaces of the test part.

The gage of FIGS. 1 through 6 show a gage for testing a groove andparticularly a thread groove. FIGS. 7 and 8 show a gage of essentiallysimilar construction designed particularly for gaging a groove, such asa groove in the rotor of a turbine for receiving the anchoring wedge ofa turbine blade. This gage shows a frame 139 having an axial guide orguideway 140, the guide particularly shown being a bore in the frame.Preferably the frame has ball grooves 146 on opposite sides forreceiving balls 141. The frame carries a pair of fixed gaging members142 secured to the frame in spaced relation such as by screws 143. Thefixed gaging members carry gaging surfaces or elements 145 correspondingwith the anchoring surfaces of the turbine or rotor groove to be gaged.The frame may carry screws 144 for obstructing the grooves for the balls141 so that they will not fall out. of the open end of the ball groove.

An operating member 147 is mounted in the guide or guideway tor axialmovement. This operating member carries an extension 148 and is receivedin the space between the fixed gaging members 142. The extensioncarriesa cooperating gaging member having a cooperating gaging surface orelement 149 on the opposite side or facing in the opposite axialdirection from the gaging surfaces 145 of the fixed gaging members.Means are provided to propel the operating member 147 axially withrespect to the frame which includes spring means 152, one end of whichengages an abutting pin 153 carried by the fram'e139 in a hole 157 andlocked in position by a screw 154 in the frame. The abutting pinprojects into and the spring is received within a hole 155 in theoperating member. The other end of the spring engages -a screw 156carried by the operating member which also may be used to adjust thecompression of the spring. An indicator is carried by a bracket on theframe, the contactor C of which indicator engages the end of theoperating member and 'hence indicates the relative position of thegaging members and the acceptability of the groove being gaged.

. In gaging a turbine blade groove, the operating member 147 is depresedto bring the gaging members and their surfaces into alignment so that itmay be inserted into the groove. The surfaces are in alignment when theshoulder on the end of the operating member 147 abuts the fixed gagingmembers 142. -When inserted, the operating member is released whereuponthe spring 152 propels the operating member 147 to the right and shiftsthe gaging surfaces 149 to theright with respect to gaging surfaces 145so that the gaging surfaces contact with opposite faces of the turbinerotor, blade groove. Each contacting surface or gaging element 145engages one side of the groove and each of the other contacting surfacesor gaging elements 149 engage its surface on the other side of the bladegroove. If the groove is too small or too large,

the indicator will show .a reading outside of the tolerance limits forthe groove. The gage is moved circumferentially to various pants of thegroove and readings taken to test the entire groove.

It is clear that the surfaces opposite from the respective surfaces 145'and 149 may be gaging surfaces from those particularly marked 145 and149 or a reverse operation in which event the spring 152 is located inthe hole on the other side of the abutment 153 to change direction ofspring propelled axial movement of the operating member 147 with respectto the frame.

FIG. 8 is an enlarged end view of the gaging members or means of FIG. 7showing a circular contour therefor. Usually in a blade anchoring groovein a turbine there is but one opening in the circumference thereof .wideenough to pass a blade and hence to pass the gaging elements of thegage. With the gaging means 142 and 148 narrow enough to pass throughthe slot into the anchoring groove, the gage may then be turned 90degrees to bring the gaging means into gaging position in the groove. Inthis way the gage may be inserted any where in the periphery of theturbine slot and it is not necessary to work the gage around the anchorgroove from the single opening thereinto.

FIG. 9 shows gaging means for gaging a blade anchoring groove in aturbine or rotor R at the pressure points alone. In this constructionthe gaging elements 142 carry gaging points 160 facing in one axialdirection to engage one surface of the groove and particularly thebottom inclined surface and the center gaging element 148 carries gagingpoints 161 which engage the pressure point on the other upper surface ofthe anchor groove G. This gaging operation is comparable to gaging thepitch diameter of a screw thread.

FIG. 10 shows another form of the gaging means in which the one gagingmember such as 148 carries gaging points 161 as described and the othergaging members or the fixed members 142 have gaging surfaces 164 whichengages the bottom of the groove and tests the distance between thebottom and the pressure point on the outer inclined surface of thegroove. It is clear that instead of providing the gaging point 161 themember may carry the gaging surface 149 FIG. 7. With a set of gages withgaging elements as described all the pertinent characteristics of ablade wedge groove may be determined.

FIG. 11 shows gaging means 166 which may be carried by the operatingmember 147 on its extension 148 and the fixed gaging members or elements167 are carried by the fixed gaging 142. The gage mounted with thesetypes of gaging members or elements can gage the overall acceptabilityof a wedge groove for the blades of a turbine having a plurality ofserrations or ridges therein.

The ball bearings 112 for rotatably mounting the frame 111 on the base93 is so constructed that there is no shake in the bearing wherebyaccurate determination of the squareness or centricity of other surfacesof the test part with respect to the screw thread is secured. This isaccomplished by selecting balls which are oversize with respect to theball space between ball races or grooves and are pressed into the ballspace. The frame 111 nevertheless rotates freely upon the base. Theballs may be oversize by about one to two ten thousandths of an inch andone and a half ten thous-andths is a desirable oversize. The balls 141are similarly selected to be oversize for the ball races or grooves andare pressed therein so that they are under compression at all times. Thespring 152 assures that the gaging. pressure is the same for all gagingoperations with the particular spring pressure setting made. If desiredthe operating member 119 of the gage of FIG. 4 may be similarly mountedon ball bearings with oversized balls.

This invention is presented to fill a need for improvements in gage withfixed spaced gaging elements. It is understood that variousmodifications in structure, as

well as changes in mode of operation, assembly, and manner of use, mayand often do occur to those skilled in the art, especially afterbenefiting from the teachings of an invention. This disclosureillustrates the preferred means of embodying the invention in usefulform.

What is claimed is: l

1. A gage for a test part with a groove having opposite surfaces andadapted to carry an indicator having a contactor comprising a framemember, an axially extending guideway carried by the frame member;operating means including an operating member mounted on the guidewayfor axial movement and having-an axis, spring means propelling theoperating member axially along the guideway, and manual means connectedwiththe operating member to move the same against the spring means,gaging means to gage the groove of the test part including fixed gagingelements spaced from each other by gaps spaced apart circumtferentiallywith respect to the axis by at least degrees and secured to the framemember, each of the fixed gaging elements having gaging ridges at leastat the edges of the gaps, the gaging ridges corresponding With thegroove of the test part, each ridge havin a gaging surface to engage oneflank surface of the groove of the test part and having an axis coaxialwith the axis of the operating member, the gaging surfaces engaging theflank surface of the test groove facing in one axial direction, movablecooperating gaging elements located in each gap between the spacedgaging elements and coaxial with the axis of the operating member andconnected with the operating member and movable thereby, and thecooperating gaging elements having at least one gaging means on theopposite side of a plane at right angles to a radial plane through onegaging means and including the axis, each gaging means being equallyspaced from the axis and corresponding with the groove of the test part,each gaging means having a gaging surface to enage opposite surfaces ofthe groove; the spring means propelling the operating member in adirection to bring the gaging means into contact With opposite surfacesof the groove to be gaged, and indicator mounting means carried by onemember and located to have an indicator contactor engage the othermember for indicating the relative position of the members and thegaging means.

2. A gage for a test part with a groove having opposite angular flanksurfaces and adapted to carry an indicator having a contactor as inclaim 1 in which the oppositely directed gaging surfaces are angularcorresponding with the angular flank surfaces of the groove of the testpart, the oppositely directed angular gaging surfaces centralizing thetest part with respect to the axis of the operating member, including anindicator carrying member, a circular bearing carried by the framemember and indicator carrying member concentric with the axis of theoperating member and the gaging means and one of said frame member andbase member being rotatable with respect to the other, and at least oneindicator mounting means carried by the indicator carrying member.

3. A gage as in claim 2 including ball bearing mounting means mountingthe operating member on the guideway, the circular bearing being ballbearing mounting means, each ball bearing mounting means including ballsand cooperating ball bearing surfaces spaced from each other to receivethe balls, and the balls being oversized by about one and a half tenthousandt'hs .of an inch for the ball spaces between cooperating ballbearing surfaces and requiring pressure for their insertion in the' ballspaces.

4. A gage as in claim 1, in which the gaging surfaces of the pair ofspaced gaging members carrying a screw thread of a plurality of turns,and the gaging surfaces of the cooperating gaging member carries asingle thread ridge on each side thereof approximately midway of thescrew thread of the pair of gaging surfaces.

5. A gage as in claim 1 in which the pair of fixed spaced gaging membershave side edges and end edges,

the cooperating gaging member has side edges and an end edge, and theedges of the spaced gaging members having gaging elements facing in oneaxial direction thereof and the cooperating gaging member having gagingelements on its edges facing in the other axial direction.

6.'A gage as in claim 5 in which one of the gaging elements is the endedge of the gaging member.

7. A gage as in claim 2 including a pivoted frame, pivot means mountingthe pivoted frame on the base member for movement towards and away fromthe gaging means, and at least one indicator mounting means carried bythe pivoted frame.

8. A gage for a test part with circular groove means having oppositeangular surfaces comprising a frame member, an axially extendingguideway carried by the frame member; operating means including anoperating member mounted on the guideway for axial movement thereon andhaving an axis, and means propelling the operating member axially alongthe guideway; means to engage the groove of the test part and tocentralize the groove of the test part with respect to the axis of theoperating member including fixed means carried by the frame member andspaced circumferentially from each other by at least two gaps, ridgemeans carried by the fixed means at least at the edges of the gaps andcorresponding to the groove of the test part, the ridge means having atleast one surface facing axially in one direction to engage one angularsurface of the groove of the test part, the ridge means having an axiscoaxial with the axis of the ope-rating member, a cooperating elementlocated in each gap and operatively connected with the operating memberand movable axially thereby in the gaps, at least one ridge on oppositesides of the cooperating element and corresponding with the groove ofthe test part and having a surface facing axially in the oppositedirection to engage the other vangular surface of the test part, theridges of the cooperating element being equally spaced from the axis ofthe operating member I; whereby the ridge means of the fixed means andridges of the cooperating element centralize the axis of the groove ofthe test part on the axis of the operating member, and a circularbearing carried by the frame member having an axis coinciding with theaxis of the operating member.

9. A gage as in claim 8 including an indicator carrying member having acooperating circular bearing received on the circular bearing of theframe member, and at least one indicator mounting means carried by theindicator carrying member, one of the members including the frame memberand the indicator carrying member being rotatable with respect to theother on the bearlugs.

10. A gage as in claim 1 including ball bearing mounting means mountingthe operating member on a guideway including balls and cooperating ballbearing surfaces spaced from each other to receive the balls, the ballsbeing oversized by about one and a half ten-thousandths of an inch forthe ball spaces between cooperating ball bearing surfaces and requiringpressure for their insertion in the ball spaces.

References Cited by the Examiner UNITED STATES PATENTS 2,087,896 7/1937Blom-strom 33-147 X 2,427,152 9/1947 Moore 33174 2,556,564 6/1951Troedson 33199 2,806,294 9/1957 Cargill 33 199 OTHER REFERENCES Allan:Rolling Bearings, Pittman Publish. Corp., N.Y., 2nd Edition, 1946 (TI1'07'1.A 55), pages 235-237.

LEONARD FORMAN, Primary Examiner.

1. A GAGE FOR A TEST PART WITH A GROOVE HAVING OPPOSITE SURFACES ANDADAPTED TO CARRY AN INDICATOR HAVING A CONTACTOR COMPRISING A FRAMEMEMBER, AN AXIALLY EXTENDING GUIDEWAY CARRIED BY THE FRAME MEMBER;OPERATING MEANS INCLUDING AN OPERATING MEMBER MOUNTED ON THE GUIDEWAYFOR AXIAL MOVEMENT AND HAVING AN AXIS, SPRING MEANS PROPELLING THEOPERATING MEMBER AXIALLY ALONG THE GUIDEWAY, AND MANUAL MEANS CONNECTEDWITH THE OPERATING MEMBER TO MOVE THE SAME AGAINST THE SPRING MEANS,GAGING MEANS TO GAGE TO GROOVE OF THE TEST PART INCLUDING FIXED GAGINGELEMENTS SPACED FROM EACH OTHER BY GAPS SPACED APART CIRCUMFERENTIALLYWITH RESPECT TO THE AXIS BY AT LEAST 90 DEGREES AND SECURED TO THE FRAMEMEMBER, EACH OF THE FIXED GAGING ELEMENTS HAVING GAGING RIDGES AT LEASTAT THE EDGES OF THE GAPS, THE GAGING RIDGES CORRESPONDING WITH THEGROOVE OF THE TEST PART, EACH RIDGE HAVING A GAGING SURFACE TO ENGAGEONE FLANK SURFACE OF THE GROOVE OF THE TEST PART AND HAVING AND AXISCOAXIAL WITH THE AXIS OF THE OPERATING MEMBER, THE GAGING SURFACESENGAGING THE FLANK SURFACE OF THE TEST GROOVE FACING IN ONE AXIALDIRECTION, MOVABLE COOPERATING GAGING ELEMENTS LOCATED IN EACH GAPBETWEEN THE SPACED GAGING ELEMENTS AND COAXIAL THE WITH AXIS OF THEOPERATING MEMBER AND CONNECTED WITH THE OPERATING MEMBER AND MOVABLETHEREBY, AND THE COOPERATING GAGING ELEMENTS HAVING AT LEAST ONE GAGINGMEANS ON THE OPPOSITE SIDE OF A PLANE AT RIGHT ANGLES TO A RADIAL PLANETHROUGH ONE GAGING MEANS AND INCLUDING THE AXIS, EACH GAGING MEANS BEINGEQUALLY SPACED FROM THE AXIS AND CORRESPONDING WITH THE GROOVE OF THETEST PART, EACH GAGING MEANS HAVING A GAGING SURFACE TO ENGAGE OPPOSITESURFACES OF THE GROOVE; THE SPRING MEANS PROPELLING THE OPERATING MEMBERIN A DIRECTION TO BRING THE GAGING MEANS INTO CONTACT WITH OPPOSITESURFACES OF THE GROOVE TO BE GAGED, AND INDICATOR MOUNTING MEANS CARRIEDBY ONE MEMBER AND LOCATED TO HAVE AN INDICATOR CONTACTOR ENGAGE THEOTHER MEMBER FOR INDICATING THE RELATIVE POSITION OF THE MEMBERS AND THEGAGING MEANS.